What does crying have to do with your emotional health?

Crying. Sobbing. Blubbering. Whatever you call it, from the time we’re babies, we all do it.

And, while many animals shed tears, emotional tears seem to be a uniquely human experience. “Tears are necessary to keep the eyeball moist, and contain proteins and other substances which maintain the eye healthy and to combat infection,” Michael Trimble, author of Why Humans Like To Cry, told Scientific American. “Humans cry for many reasons, but crying for emotional reasons and crying in response to aesthetic experiences are unique to us.”

And whether it’s tears of joy or sorrow, the moments that cause us to choke up can tell us a lot about ourselves.

“Crying, as well as other sorts of intense emotional experience, can help highlight for us what’s important and what we need to focus on,” Lauren Bylsma, Ph.D., a post doctoral scholar at the University of Pittsburgh, who has conducted multiple studies and written several papers on tears and crying, tells HuffPost.

But for such a universal experience, many of us know surprisingly little about the tears we cry. So we collected 13 lesser-known facts about tears—read ’em and weep.